1. Field of the Invention
The present invention relates generally to spray stream nozzles employed in dispensing wet chemical photoresist developer solutions for developing photoexposed blanket photoresist layers within integrated circuits. More particularly, the present invention relates to an apparatus incorporating a spray stream nozzle, and a method for cleaning the spray stream nozzle, to avoid clogging of the spray stream nozzle when employed in dispensing wet chemical photoresist developer solutions for developing photoexposed blanket photoresist layers within integrated circuits.
2. Description of the Related Art
In the method within integrated circuit fabrication for developing latent images within photoexposed blanket photoresist layers to form patterned photoresist layers from those photoexposed blanket photoresist layers, it has become common in the art to employ a spray stream nozzle to dispense a wet chemical photoresist developer solution employed in developing a patterned photoresist layer from the photoexposed blanket photoresist layer. The use of spray stream nozzles is desirable since in addition to efficiently providing a metered amount of wet chemical photoresist developer solution upon a photoexposed blanket photoresist layer the wet chemical photoresist developer solution is also provided to the photoexposed blanket photoresist layer surface at an accelerated velocity which assists in dissolving appropriate portions of the photoexposed blanket photoresist layer to form the desired patterned photoresist layer.
While the use of spray stream nozzles to dispense upon photoexposed blanket photoresist layers within integrated circuits uniformly metered photoresist developer solutions at enhanced linear velocities has become quite common in the art, the use of such spray stream nozzles to deliver uniformly metered photoresist developer solutions at enhanced linear velocities is not entirely without problems. In particular, it is known in the art that spray stream nozzles which are commonly employed to dispense upon photoexposed blanket photoresist layers within integrated circuits photoresist developer solutions are susceptible to clogging which substantially impedes the desired photoresist developer flow through the nozzle. In addition, the clogging may also lead to particulate residue deposition upon photoexposed blanket photoresist layers desired to be developed through contact with the photoresist developer solution. The clogging presumably derives from recrystallization within the spray stream nozzle of solids typically dissolved in the photoresist developer solution. The particulate residue deposition presumably derives from deposition of recrystallized solids forced through a partially clogged spray stream nozzle. Such recrystallized solids typically include recrystallized active agents within the photoresist developer solution, as well as recrystallized surfactants and other additives commonly incorporated into the photoresist developer solution. The clogging and particulate deposition are particularly prevalent as diameters of apertures within spray stream nozzles approach the range of about 0.05 to about 0.2 millimeters (mm), which range is commonly employed to achieve the enhanced photoresist developer solution linear velocities desired for developing photoexposed blanket photoresist layers within advanced integrated circuits.
Thus, it is desirable in the art of integrated circuit fabrication to provide a method for cleaning a spray stream nozzle employed in dispensing a photoresist developer solution upon a photoexposed blanket photoresist layer so that: (1) clogging of the spray stream nozzle may be avoided; and (2) particulate residue deposition from the spray stream nozzle onto the photoexposed blanket photoresist layer may also be avoided. It is towards providing a method and a spray stream nozzle in accord with these goals that the present invention is directed.
Methods and apparatus through which clogging of spray nozzles may be avoided or through which clogged spray nozzles may be cleaned are disclosed in the art. For example, Hethcoat in U.S. Pat. No. 5,183,066 discloses a spray nozzle cleaning apparatus and spray nozzle cleaning method appropriate for cleaning spray nozzles employed in paint spray guns. In addition, Abiko in U.S. Pat. No. 5,435,488 discloses a spray nozzle employed in spraying solvent borne coatings and adhesives, as well as a method through which the spray nozzle may be employed. The spray nozzle exhibits reduced susceptibility to clogging.
Desirable in the art are additional methods and apparatus through which a spray stream nozzle employed in dispensing a wet chemical photoresist developer solution onto a photoexposed blanket photoresist layer within an integrated circuit may be cleaned to avoid: (1) clogging of the spray stream nozzle; or (2) deposition from the spray stream nozzle of a particulate residue upon the photoexposed blanket photoresist layer.